Sodium Methoxide PET Depolymerization for Larger Feedstock Particles

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Solution Overview

Problem

There is a need for an efficient, low-energy, and cost-effective process to produce dimethyl terephthalate (DMT) and mono ethylene glycol (MEG) from polyethylene terephthalate (PET) that can handle larger feedstock particles and reduce impurities, while maintaining high yields.

Innovation Solution

A process involving the depolymerization of PET using methanol and sodium methoxide, where PET is mixed with a first portion of methanol, followed by the addition of sodium methoxide and subsequent portions of methanol to form DMT and MEG, allowing for the use of larger particle sizes and achieving high yields of DMT and MEG with minimal impurities.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional depolymerization methods are used, then DMT and MEG can be produced, but the process requires fine particle feedstock and generates impurities

Engineering Contradiction:
Improvefeedstock particle size requirementVSAvoidprocess complexity
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent changes the chemical parameters of the depolymerization process by using sodium methoxide as a catalyst and controlling the methanol-to-PET ratio, which allows the process to work effectively with larger feedstock particles while maintaining high product purity and yield

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

Sodium methoxide serves as an intermediary catalyst that facilitates the depolymerization reaction, enabling the process to handle larger particles and reduce impurity formation without compromising the production of DMT and MEG

Inventive Principle:
Principle #24Intermediary (Mediator)

2Productivity

If existing depolymerization processes are used, then DMT and MEG are produced, but energy consumption is high and yields are limited

Engineering Contradiction:
ImproveDMT and MEG yieldVSAvoidenergy consumption
Core Design Contradiction:
ProductivityVSUse of energy by moving object

Solution Approach 1:

The patent optimizes reaction parameters including temperature, methanol concentration, and catalyst amount to achieve higher yields of DMT and MEG while reducing energy consumption compared to conventional methods

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The process maintains continuous depolymerization reaction conditions with controlled methanol addition and temperature maintenance, ensuring sustained high yield production while minimizing energy waste through efficient heat management

Inventive Principle:
Principle #20Continuity of useful action

3Reliability

If conventional methods are used, then depolymerization occurs, but impurities are generated and yields are reduced

Engineering Contradiction:
Improveproduct purityVSAvoidDMT and MEG yield
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

Sodium methoxide acts as a selective catalyst that promotes the desired depolymerization reaction while minimizing side reactions that generate impurities, thereby achieving both high product purity and high yield simultaneously

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent controls reaction conditions including temperature, methanol-to-PET ratio, and catalyst concentration to optimize the balance between product purity and yield, preventing impurity formation while maintaining high production efficiency

Inventive Principle:
Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The process achieves high yields of DMT and MEG, with DMT yields of at least 90 mol% and MEG yields of at least 80 mol%, while accommodating larger feedstock particles and minimizing impurities, thus addressing the inefficiencies of existing methods.

Implementation Method 1

adding sodium methoxide to the first mixture

Methodology Applied
Scientific EffectCatalysis: Catalysis

Implementation Method 2

The polyethylene terephthalate (PET) bottle resin market has been growing strongly as PET resins have replaced glass in carbonated soft drink, bottled water and food containers. Dimethyl terephthalate (DMT) is primarily used in the manufacture of polyethylene terephthalate (PET)

Methodology Applied
Scientific EffectMethanolysis: Hydrolysis

Data Source

PatentUS12415901B2Process for the depolymerization of polyethylene terephthalate (PET)
Publication Date: 2025.09.16 9449710 CANADA INC

AI summary

The present disclosure relates to the formation of dimethyl terephthalate (DMT) and mono ethylene glycol (MEG). The present invention also relates to the depolymerization of polyethylene terephthalate (PET) and the recovery of dimethyl terephthalate (DMT) and mono ethylene glycol (MEG) using sodium methoxide as a catalyst.